{
 Makarova Liza
 25.09.12
 Programma schitaet udvoennuyu ploshad treugolnika.
}
program Ploshad;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  x1, y1, x2, y2, x3, y3, S: integer;

begin
  write ('First point: ');
  readln (x1, y1);
  write ('Second point: ');
  readln (x2, y2);
  write ('Third point: ');
  readln (x3, y3);
  S:= abs(2*(x2 - x1) * (y3 - y1) - ((x3 - x1) * (y3 - y1) + (x2 - x3) * (y3 - y2) + (x2 - x1) * (y2 - y1)));
  writeln ('2S=', S);
  readln;
end.
